Organic light-emitting diode (OLED) devices include top-emission type OLEDs. The top-emission OLED emits light from a cathode layer so that the cathode layer is required to possess not only excellent electron injection capability and relatively lower square resistance, but also better light transmittance.
Existing cathode layer has poor light transmittance, and has to be made extremely thin in order to ensure a better light transmittance. However, this may cause increased square resistance, raised driving voltage, and also decreased voltage stability. To solve such problem, the prior art proposes a solution in which a graphene auxiliary cathode layer is manufactured on the cathode layer. However, a material of the graphene auxiliary cathode layer is totally different in the type from that of the cathode layer, and hence has to be manufactured by a different process, which results in increased process-based complexity and reduced production efficiency.